Fix crash when closing output window from outer session

Emitting the close event needs to happen before
container_output_destroy, because container_output_destroy sets the
sway_output to NULL and sway_output is used in IPC.

sway/tree/container.c

@@ -304,6 +304,9 @@ struct sway_container *container_destroy_noreaping(struct sway_container *con) {
 		return NULL;
 	}
 
+	wl_signal_emit(&con->events.destroy, con);
+	ipc_event_window(con, "close");
+
 	// The below functions move their children to somewhere else.
 	if (con->type == C_OUTPUT) {
 		container_output_destroy(con);
@@ -325,9 +328,6 @@ struct sway_container *container_destroy_noreaping(struct sway_container *con) {
 		}
 	}
 
-	wl_signal_emit(&con->events.destroy, con);
-	ipc_event_window(con, "close");
-
 	con->destroying = true;
 	list_add(server.destroying_containers, con);